School of Biological Science and Center for Plant Science Innovation, University of Nebraska, Lincoln, NE, USA.
Center for Tropical Forest Science-Forest Global Earth Observatory, Smithsonian Institute, Washington DC, USA.
Nat Ecol Evol. 2021 Feb;5(2):174-183. doi: 10.1038/s41559-020-01340-9. Epub 2020 Nov 16.
Resource allocation within trees is a zero-sum game. Unavoidable trade-offs dictate that allocation to growth-promoting functions curtails other functions, generating a gradient of investment in growth versus survival along which tree species align, known as the interspecific growth-mortality trade-off. This paradigm is widely accepted but not well established. Using demographic data for 1,111 tree species across ten tropical forests, we tested the generality of the growth-mortality trade-off and evaluated its underlying drivers using two species-specific parameters describing resource allocation strategies: tolerance of resource limitation and responsiveness of allocation to resource access. Globally, a canonical growth-mortality trade-off emerged, but the trade-off was strongly observed only in less disturbance-prone forests, which contained diverse resource allocation strategies. Only half of disturbance-prone forests, which lacked tolerant species, exhibited the trade-off. Supported by a theoretical model, our findings raise questions about whether the growth-mortality trade-off is a universally applicable organizing framework for understanding tropical forest community structure.
树木内部的资源分配是一种零和博弈。不可避免的权衡取舍决定了促进生长的资源分配会抑制其他功能,从而在生长与生存之间产生投资梯度,树种会根据这一梯度进行调整,这被称为种间生长-死亡率权衡。这一范式被广泛接受,但尚未得到充分证实。本研究使用了十个热带森林中 1111 个树种的种群动态数据,通过描述资源分配策略的两个种特异性参数(资源限制的耐受性和对资源获取的分配响应性),检验了生长-死亡率权衡的普遍性,并评估了其潜在驱动因素。结果表明,全球范围内存在典型的生长-死亡率权衡,但这种权衡仅在受干扰程度较低的森林中表现得较为强烈,这些森林中包含了多种资源分配策略。只有一半受干扰程度较高的森林表现出了这种权衡,而这些森林中缺乏耐受物种。理论模型的支持进一步表明,我们的研究结果对生长-死亡率权衡是否是理解热带森林群落结构的普遍适用的组织框架提出了质疑。